Sunscreens - more harm than good?

What are sunscreens? Sunscreens are personal care products that help protect the skin from harmful effects of the sun. While small amounts of ultraviolet radiation (UV) from the sun are essential for the production of vitamin D, prolonged or over-exposure to UV can result in short- and long-term health effects. These range from sunburn, to premature skin ageing, to skin cancer. Australia has the highest skin cancer rate in the world.

Sunscreens work either by absorbing or reflecting UV. The main components of sunscreens that provide this protective property are called ‘UV filters’. There are two main categories of UV filters: ‘organic filters’ absorb UV light – these are often called ‘chemical’ sunscreens; while ‘inorganic filters’ or ‘mineral filters’ scatter and reflect UV light. One or both types may be used in a product, since different UV filters are effective against different UV wavelengths.

Antioxidants are another type of ingredient used in some sunscreens. Because UV filters do not prevent all UV radiation from reaching the skin, addition of antioxidant ingredients helps counteract free radicals that may form from the small amount of UV radiation that does reach the skin.​Sunscreens are available in many varieties which include:

A range of sun protection factors (SPFs), with a higher SPF indicating a greater degree of sun protection from UVB (short wavelength UV)

Broad spectrum, which acts against the effects of both UVA (long wavelength UV) and UVB

Water resistant

Different consistencies such as creams, lotions, milks, gels, sticks and sprays

What’s the myth?There are a number of myths surrounding sunscreens, which unfortunately may be deterring consumers from using these important products as part of their sun protection regime.

One common myth is that sunscreens containing nanoparticles are unsafe. Nano-scale[1] zinc oxide and titanium dioxide are used as highly effective broad-spectrum UV filters in some sunscreens. The hypothetical concern is that nanoparticles, due to their small size, may penetrate the skin and cause an unknown range of harmful effects to the body.

Other common sunscreen ingredients such as retinyl palmitate (vitamin A) and oxybenzone also continue to be the target of unfounded health claims. To read more about these myths, please click on the sunscreen ingredients link.

FACT: There is no evidence that nano-scale sunscreen ingredients penetrate the skinIn order for nanoparticles to cause harm to the body, they must first penetrate the skin. Secondly, they must have some toxic effect on the body.

The healthy skin is an effective barrier to particles and microorganisms. It consists of an outer protective layer of dead skin cells (the stratum corneum), under which is the living tissue of the dermis.

According to a 2016 article published in the Medical Journal of Australia, many studies have shown metal oxide nanoparticles do not readily penetrate the skin’s outer layer.[2]Associate Professor Paul Wright from RMIT University in Melbourne identifies that nano-sunscreens "are formulated to remain on the skin’s surface, which is constantly shedding its outer layer of dead cells”.[3]

The Therapeutic Goods Administration (TGA) has conducted ongoing reviews of research into the safety of nanoparticles used in sunscreens. According to their 2009 review, “the current weight of evidence suggests that titanium dioxide and zinc oxide nanoparticles do not reach viable skin cells, rather, they remain on the surface of the skin and in the outer layer (stratum corneum) of the skin that is composed of non-viable, keratinized cells”.[4] This conclusion was reiterated following their 2013 Literature Review, which stated "none of the studies provided any evidence that nano-sized ZnO particles are able to cross the skin barrier in intact or compromised skin".[5] The EU’s Scientific Committee on Consumer Safety also published their Opinion that there is no evidence that zinc oxide nanoparticles are absorbed through the skin.[6]

There is less available evidence on penetration of nanoparticles through damaged skin. However, a 2008 review concluded that, “there is little evidence suggesting slightly compromised skin has a greater susceptibility to skin penetration of topically applied substances”, on the basis that no absorption of nano-scale titanium dioxide through normal and psoriatic skin was observed.[7]

FACT: There is no evidence that nano-scale sunscreen ingredients are toxic to peopleIn addition to the evidence against skin penetration of nano-scale sunscreen ingredients, the weight of evidence also indicates that these ingredients are not toxic.

The 2009 TGA review states that “currently, there is no in vivo evidence to indicate possible toxicity of nanoparticulate titanium dioxide or zinc oxide in people using sunscreens”.[4]

This review also reports on the finding that nano-scale titanium dioxide, even when injected below the skin, was found to be non-toxic. This provides a good indication that, even if this ingredient were to penetrate the skin, it would not cause harm.

FACT: Nano-scale sunscreen ingredients are not newNano-scale zinc oxide and titanium dioxide are used in some sunscreens as highly effective broad-spectrum UV filters. These ingredients are not new. According to the TGA’s 2009 review, “nanosized titanium dioxide particles have been used in sunscreens since at least 1990 and nanosized zinc oxide since 1999”.[4]

Conventional zinc oxide and titanium dioxide have been used as sunscreens for many years. These ingredients are excellent sunscreens as they have a broad spectrum of action, blocking both UVA and UVB, but they leave a white film on the skin, which makes these products less appealing to consumers.

Nano-scale zinc oxide and titanium dioxide have the advantages of being transparent, as well as easier to apply. And their smaller size enables better skin coverage – and therefore better sun protection, according to President of the American Academy of Dermatology.[8]

FACT: Industry has responded to calls for nano-labellingThere is no evidence that the nano-scale UV filters used in sunscreens pose any health risk for consumers. Nevertheless, industry has responded to calls for more information about nano-scale ingredients in sunscreen and cosmetic products to be made available to consumers.

The proposal would provide Australian consumers with the information they need to make informed choices, providing transparency within the Australian sunscreen and cosmetic market. And, because this approach mirrors the EU nano-labelling approach, which has also been taken up in New Zealand, it will also assist in international trade through alignment of labelling requirements.

So far, however, government has rejected industry’s proposal. The basis for this rejection is that there are no safety issues regarding these nano-scale ingredients.

FACT: All sunscreens in Australia are regulated for safety.Australia has a uniquely high level of regulatory oversight for sunscreens.

Primary sunscreens (intended primarily for sun protection of the skin) with SPF4 or greater, and secondary sunscreens (intended primarily for a purpose other than sunscreening) with SPF greater than 15 are regulated by the TGA and are required to list active ingredients on the label. Ongoing review of the use of sun protection products containing nanoparticle zinc oxide and titanium dioxide is being undertaken by the TGA.

All other secondary sunscreens are regulated as cosmetics by the national industrial chemical regulator NICNAS. Secondary sunscreens are required to disclose all intentionally added ingredients, as regulated by the Australian Competition & Consumer Commission. In most other developed nations, including the EU and New Zealand, sunscreens are regulated as cosmetics. In the USA and Canada, whilst sunscreens are regulated as over-the-counter medicines, the level of regulatory intervention is much lower than in Australia.

The bottom line? You can continue to use sunscreen products, including those containing nano-scale titanium dioxide and zinc oxide, with confidence that these products are safe and effective sunscreens.​Cancer experts warn against avoidance of sunscreen on the basis of hypothetical risks, whereas there are known risks associated with excessive sun exposure. As Associate Professor Paul Wright puts it, "the danger of excessive UV light itself with respect to skin damage and cancer is far greater than the perceived risk posed by nano-sunscreens, which is not supported by the scientific literature”.[3] Similarly, according to the NSW Cancer Council, “At the moment 1,600 people die from skin cancer every year. It is almost entirely preventable. It is a lot more harmful to stop wearing sunscreen.”[9]